You are probably right in terms of pass distribution. I think the conclusion you draw is that given the low % to Barber and his stellar rushing stats thusfar........the majority of Mannings yards are coming off play action either down the field to Buress or the outlet to Shockey.

The Vikings need to craft their defense plan around these facts. Stop the run, minimizing the play action effect, and force Manning to read the field and beat you with his mind and arm. And so, disruption and causing havoc in the backfield is the key for the Vikings.